I have the same situation in the garage, 5-15 GFI on 20amps breaker on the board. I would get UL-listed charger and not something Chinese that can cause fire. These chargers are usually 12amps. I decided to skip on the charger all together as I live 5 mins of walking from Electrify America charger 
Also I noticed the tires have measly 300 thread wear rating on them. Meaning they might well be under 4/32 after two years. Wonder how is Mercedes when in comes to buying used tire set for pennies, if they have same/better characteristics and are run flats but of a different brand, as new set is $1800 easily.